Micro Week 2

Question 1

GI system defenses

Answer 1

General: epithelium, mucus, peristalsis
Mouth: Saliva (lysozyme, IgA, lactoferrin, etc.), normal flora
Stomach: acid, normal flora??
Intestine: Peyer’s patches, normal flora

Question 2

Dental Carries

Answer 2

Infectious disease that causes tooth decay

Pain, tooth loss, spread of infection

Risk factors: high-sugar diet, poor oral hygeine, reduced saliva, smoking, periodontal disease

Health disparities issue: AI/AN have highest prevalence of carries in US

Caused by fermentable sugars and acid producing bacteria creating demineralization.

Question 3

Gingivitis

Answer 3

Periodontal disease is infectious disease destroying supporting structures of teeth.

Affects more than 30% of population worldwide

Mild and common form is gingivitis = irritation, redness, and swelling.

Reversible w/ good cleaning and oral care

Question 4

Periodontitis

Answer 4

Infection of underlying tissues and bones

Associated w/ MI, stroke, lung disease, premature birth, DM

Inflammation believed to be mediating factor (poverty?!)

Rx goal: thouroughly clean all surfaces to prevent further bone damage. Scaling, root planing, topical amoxicillin/metronidazole

Question 5

Biofilm

Answer 5

Two or more species of bacterial microcolonies in glycocalyx.

Why live in a biofilm?

• adherence
• protection from immune system
• protection from abx
• symbiotic relationships
• local conditions of pH, etc. in a normally inhospitable environment

Question 6

Mouth Normal Flora

Answer 6

Strep mitis “group” - S. sanguinis, S. oralis, S. gordonii, and S. mitis

Gram positive lactobacilli and spirochetes

Gram positives –> plaques that cause carries

Gram negatives –> subgingival space –> periodontal disease

Question 7

Strep mutans

Answer 7

Common cause of carries

Gram + 
Cocci
Catalase neg
Fac anaerobe
a Hemolytic (Viridans group)
Optochin resistant

Virulence factors:

• Adhesin-like surface-associated proteins (AgI/II) that are capable of binding to receptors in pedicle
• Extracellular glucosyltrasnferases (Gtfs) are constituents of pellicle that synthesize glucans from sucrose to provide additional S. mutans binding sites

Question 8

Keystone pathogens in periodontal disease

Answer 8

Orchestrate damage (think pocket-gophers on prairie) by remodeling a normally symbiotic microbiota into a dysbiotic state

Treponema denticola
Tannerella forsythia
Porphyromonas gingivalis (best studied)

*Aggregatibacter actinomycetmcomitans is related to the severity of periodontal disease

Question 9

Microbes involved in periodontal disease

Answer 9

P. gingivalis
C gingivalis
Prevotell denticola

Question 10

Ludwig’s angina

Answer 10

Skin infx in floor of mouth from untreated dental infxs. Swelling of infected area may block airway or prevent saliva swallowing.

Sx: Breathing difficulty, confusion/mental changes, fever, neck pain, neck swelling, redness of neck, weakness, fatigue, excess tiredness

Question 11

Candidiasis

Answer 11

Creamy white lesions, usually on tongue or inner cheeks. Sometimes spreading to roof, gums, tonsils, pharynx, or esophagus (dangerous)

Dx: scrapes off –> hyphae w/ 45 degree buds.

Rx: Topical clotrimazole lozenge and nystatin swish and swallow. Advance to fluconazole and amphotericin for resistant strains.

Question 12

Hairy Leukoplakia

Answer 12

Caused by EBV in HIV + patients.

Fuzzy white patches on side of tongue that can’t be wiped away.

Double stranded
Linear
DNA
Enveloped
HHV-4 (EBV)

Question 13

H. pylori

Answer 13

Gram negative
Flagellated helix-shaped rod (spirilli)
Microaerophilic
Catalase +
Oxidase +
Urease +

Infects 50% of US and almost 100% of world. (10-20% lifetime risk of ulcer and 1-2% distal gastric cancer)

Depends on strain of H. pylori, immune response, and gastric microbiome

Virulence factors:
Key:
-VacA - pore forming cytotoxin that allows leakage of Ca++ from epithelial cells
-CagA: Type 4 secretion system (TFSS) - a needle through which CagA travels to host cytosol and affects the proliferative activities, adhesion, and cytoskeletal organization of cells. Highly proinflammatory!
-Inhibit phagocytic uptake
-Inhibit adaptive immune response
-Evade killing by ROS and NO
-Evade recognition by pattern recognition receptors
-Adhesins
-Flagella-based motility

Causes and ulcer by:

1. attracting inflammatory cells
2. inflammatory cells cannot kill easily
3. host damages itself by continual and innefective immune response

Dx: Endoscopy and culture (expensive and risky), breath test, stool test, blood test (can’t confirm cure)

Can cause MALT lymphoma and gastric carcinoma. Reduced risk of esophageal carcinoma.